SkXMLParser.cpp 5.9 KB

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  1. /*
  2. * Copyright 2006 The Android Open Source Project
  3. *
  4. * Use of this source code is governed by a BSD-style license that can be
  5. * found in the LICENSE file.
  6. */
  7. #include "src/xml/SkXMLParser.h"
  8. #include "expat.h"
  9. #include "include/core/SkStream.h"
  10. #include "include/core/SkString.h"
  11. #include "include/core/SkTypes.h"
  12. #include "include/private/SkTo.h"
  13. static char const* const gErrorStrings[] = {
  14. "empty or missing file ",
  15. "unknown element ",
  16. "unknown attribute name ",
  17. "error in attribute value ",
  18. "duplicate ID ",
  19. "unknown error "
  20. };
  21. SkXMLParserError::SkXMLParserError() : fCode(kNoError), fLineNumber(-1),
  22. fNativeCode(-1)
  23. {
  24. reset();
  25. }
  26. SkXMLParserError::~SkXMLParserError()
  27. {
  28. // need a virtual destructor for our subclasses
  29. }
  30. void SkXMLParserError::getErrorString(SkString* str) const
  31. {
  32. SkASSERT(str);
  33. SkString temp;
  34. if (fCode != kNoError) {
  35. if ((unsigned)fCode < SK_ARRAY_COUNT(gErrorStrings))
  36. temp.set(gErrorStrings[fCode - 1]);
  37. temp.append(fNoun);
  38. } else
  39. SkXMLParser::GetNativeErrorString(fNativeCode, &temp);
  40. str->append(temp);
  41. }
  42. void SkXMLParserError::reset() {
  43. fCode = kNoError;
  44. fLineNumber = -1;
  45. fNativeCode = -1;
  46. }
  47. ////////////////
  48. namespace {
  49. const XML_Memory_Handling_Suite sk_XML_alloc = {
  50. sk_malloc_throw,
  51. sk_realloc_throw,
  52. sk_free
  53. };
  54. struct ParsingContext {
  55. ParsingContext(SkXMLParser* parser)
  56. : fParser(parser)
  57. , fXMLParser(XML_ParserCreate_MM(nullptr, &sk_XML_alloc, nullptr)) { }
  58. void flushText() {
  59. if (!fBufferedText.isEmpty()) {
  60. fParser->text(fBufferedText.c_str(), SkTo<int>(fBufferedText.size()));
  61. fBufferedText.reset();
  62. }
  63. }
  64. void appendText(const char* txt, size_t len) {
  65. fBufferedText.append(txt, len);
  66. }
  67. SkXMLParser* fParser;
  68. SkAutoTCallVProc<skstd::remove_pointer_t<XML_Parser>, XML_ParserFree> fXMLParser;
  69. private:
  70. SkString fBufferedText;
  71. };
  72. #define HANDLER_CONTEXT(arg, name) ParsingContext* name = static_cast<ParsingContext*>(arg)
  73. void XMLCALL start_element_handler(void *data, const char* tag, const char** attributes) {
  74. HANDLER_CONTEXT(data, ctx);
  75. ctx->flushText();
  76. ctx->fParser->startElement(tag);
  77. for (size_t i = 0; attributes[i]; i += 2) {
  78. ctx->fParser->addAttribute(attributes[i], attributes[i + 1]);
  79. }
  80. }
  81. void XMLCALL end_element_handler(void* data, const char* tag) {
  82. HANDLER_CONTEXT(data, ctx);
  83. ctx->flushText();
  84. ctx->fParser->endElement(tag);
  85. }
  86. void XMLCALL text_handler(void *data, const char* txt, int len) {
  87. HANDLER_CONTEXT(data, ctx);
  88. ctx->appendText(txt, SkTo<size_t>(len));
  89. }
  90. void XMLCALL entity_decl_handler(void *data,
  91. const XML_Char *entityName,
  92. int is_parameter_entity,
  93. const XML_Char *value,
  94. int value_length,
  95. const XML_Char *base,
  96. const XML_Char *systemId,
  97. const XML_Char *publicId,
  98. const XML_Char *notationName) {
  99. HANDLER_CONTEXT(data, ctx);
  100. SkDebugf("'%s' entity declaration found, stopping processing", entityName);
  101. XML_StopParser(ctx->fXMLParser, XML_FALSE);
  102. }
  103. } // anonymous namespace
  104. SkXMLParser::SkXMLParser(SkXMLParserError* parserError) : fParser(nullptr), fError(parserError)
  105. {
  106. }
  107. SkXMLParser::~SkXMLParser()
  108. {
  109. }
  110. bool SkXMLParser::parse(SkStream& docStream)
  111. {
  112. ParsingContext ctx(this);
  113. if (!ctx.fXMLParser) {
  114. SkDebugf("could not create XML parser\n");
  115. return false;
  116. }
  117. XML_SetUserData(ctx.fXMLParser, &ctx);
  118. XML_SetElementHandler(ctx.fXMLParser, start_element_handler, end_element_handler);
  119. XML_SetCharacterDataHandler(ctx.fXMLParser, text_handler);
  120. // Disable entity processing, to inhibit internal entity expansion. See expat CVE-2013-0340.
  121. XML_SetEntityDeclHandler(ctx.fXMLParser, entity_decl_handler);
  122. static const int kBufferSize = 512 SkDEBUGCODE( - 507);
  123. bool done = false;
  124. do {
  125. void* buffer = XML_GetBuffer(ctx.fXMLParser, kBufferSize);
  126. if (!buffer) {
  127. SkDebugf("could not buffer enough to continue\n");
  128. return false;
  129. }
  130. size_t len = docStream.read(buffer, kBufferSize);
  131. done = docStream.isAtEnd();
  132. XML_Status status = XML_ParseBuffer(ctx.fXMLParser, SkToS32(len), done);
  133. if (XML_STATUS_ERROR == status) {
  134. XML_Error error = XML_GetErrorCode(ctx.fXMLParser);
  135. int line = XML_GetCurrentLineNumber(ctx.fXMLParser);
  136. int column = XML_GetCurrentColumnNumber(ctx.fXMLParser);
  137. const XML_LChar* errorString = XML_ErrorString(error);
  138. SkDebugf("parse error @%d:%d: %d (%s).\n", line, column, error, errorString);
  139. return false;
  140. }
  141. } while (!done);
  142. return true;
  143. }
  144. bool SkXMLParser::parse(const char doc[], size_t len)
  145. {
  146. SkMemoryStream docStream(doc, len);
  147. return this->parse(docStream);
  148. }
  149. void SkXMLParser::GetNativeErrorString(int error, SkString* str)
  150. {
  151. }
  152. bool SkXMLParser::startElement(const char elem[])
  153. {
  154. return this->onStartElement(elem);
  155. }
  156. bool SkXMLParser::addAttribute(const char name[], const char value[])
  157. {
  158. return this->onAddAttribute(name, value);
  159. }
  160. bool SkXMLParser::endElement(const char elem[])
  161. {
  162. return this->onEndElement(elem);
  163. }
  164. bool SkXMLParser::text(const char text[], int len)
  165. {
  166. return this->onText(text, len);
  167. }
  168. ////////////////////////////////////////////////////////////////////////////////
  169. bool SkXMLParser::onStartElement(const char elem[]) {return false; }
  170. bool SkXMLParser::onAddAttribute(const char name[], const char value[]) {return false; }
  171. bool SkXMLParser::onEndElement(const char elem[]) { return false; }
  172. bool SkXMLParser::onText(const char text[], int len) {return false; }